Three Muscle Fiber Types and How to Train Them

It is very important to choose a workout program that will stimulate the muscle fiber type you need in order to reach the results you are striving for. 

Different lifts, exercises and rep ranges will stimulate different muscle fiber types. There are three different muscle fiber types that make up the entire muscle tissue.

Type A Fast-Twitch Muscle Fibers

The first type of muscle fiber is known as Type A Fast -Twitch muscle fibers. They are the fibers responsible for the most powerful contractions produced, but also fatigue the quickest.

Type A fibers are used mainly for power lifting movements with low rep ranges.

They have have a low oxygen capacity and can’t utilize the body’s oxygen supply very well. This is why these particular muscle fibers are not built for endurance exercises.

Creatine phosphate and stored muscle glycogen (glucose) are used to fuel these muscle fibers. Type A muscle fibers do not utilize the body’s stored body fat (fat burning) because the contractions are very quick and short lasting.

Type B Fast-Twitch Muscle Fibers

The second type of muscle fiber is known as Type B Fast- Twitch muscle fibers. These are still fast twitch fibers, but not to the extent of Type A.

These fibers are not “all out explosive contractions” like the Type A. These are still explosive, powerful movements, but not “all out”. Usually this type of muscle fiber will be used with 80-90% effort.

They have higher oxygen capacity than Type A, so there is a little more endurance involved with the exercise, allowing them to contract for a longer period of time.

Slow Twitch

The third type of muscle fiber is known as slow twitch. This is the muscle fibers you would use to do high repetitions or long distance running.

These fibers do not fatigue very easily due to their high oxygen capacity. They contract slowly with a small amount of force-not producing a great deal of power.

These muscle fibers rely heavily on the body’s fat as fuel. This is the “fat burning” effect that people look for when doing long cardio sessions.

How to Train the Different Muscle Types

Now that you learned a little bit about the three different muscle fiber types it is time to learn how to stimulate them properly.

When training Type A fibers you will want to do something at all out force for a short duration. For example, full speed sprinting intervals and 3-5 rep sets for weightlifting.

To train your Type B muscle fibers you want to slightly decrease your muscle contraction force, while you increase the length of your muscle contractions. For example, do sprints at 30-45 sec. intervals at 80-90% effort and for weightlifting target the 6-10 rep/set range.

Last are your slow twitch muscle fibers. To train them you need endurance. They are made to last for long periods of time, so whatever you are training for try to continually do it longer and longer. For example, keep increasing your distance in running and continue to increase the amount of reps you do in weightlifting.

Depending on your sport and training goals you must train in a way that will improve your performance, producing the specific results you are looking to achieve.

Understanding how to train the different muscle fibers will increase your ability to build muscle and shed fat quickly.